System for biodegradation of oxyanions such as perchlorate on ion exchange resins

ABSTRACT

Systems and methods for removing perchlorate load off of ion exchange resins are disclosed. The systems and methods rely upon direct contact between the resin and a liquid product formed by the culturing of perchlorate-destroying microorganisms. These methods can be incorporated into methods for removing perchlorate from aqueous streams. A resin product comprising an anion exchange resin with a coating of perchlorate-destroying microorganisms on its surface is also disclosed.

REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 60/484,949, filed on Jul. 2, 2003 and is a divisional of U.S.Patent Application Ser. No. 10/789,432, filed on Feb. 26, 2004 both ofwhich are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention pertains to the field of water treatment and to the useof ion (anion) exchange resins to remove contaminants such asperchlorate ions from aqueous feed stocks ranging from domestic,industrial and agricultural water supplies such as drinking water tobrines and other aqueous streams. More particularly, this inventionrelates to the removal of perchlorate load from perchlorate-loadedresins loaded by use in water treatment so as to permit reuse or safedisposal of the resin.

2. Background Information

Ammonium perchlorate has been used for the past 50 years as an oxidizercomponent in solid explosives and solid propellants for rockets,missiles and fireworks. It is estimated that well over 90% of theammonium perchlorate produced in the United States is used in theseapplications. Casual handling of perchlorates and perchlorate-ladeneffluents by manufacturers, and the build up of poorly-containedstockpiles of outdated missile and rocket fuels have resulted inperchlorate contamination of surface water and ground water supplies.Perchlorate contamination is a growing problem in at least 14 Westernstates in the United States and has been reported in Europe as well.

The California Department of Health Services has established an actionlevel for perchlorate of 18 ug/l. This is based upon the potential forperchlorate to inhibit the uptake of iodine by the thyroid gland.Perchlorate levels of up to several hundred ug/l have been found inground water in California and other states.

Two approaches to removing perchlorate from water supplies are beingresearched extensively—biological destruction and ion exchange.Biological destruction using various bacterial strains has beendescribed at the Federal Remediation Technologies Roundtable GeneralMeeting held on May 30, 2001 where Jeffrey Marqusee described howbiological organisms could attack perchlorate in subsurfaceenvironments. Similar studies were also reported at that meeting by PaulHatzinger (Poster Number 43) and by John D. Coates (Poster Cleanup CU45).

Ion exchange is attractive because perchlorate has a very high affinityfor common polystyrene-based strong base anion exchange resins. However,state of the art practice does not provide a practical and convenientmethod for regeneration of the resin. This is due at least in part toperchlorate's affinity for the common resins being so strong that verylarge quantities of concentrated sodium chloride brine are required todisplace the perchlorate during regeneration. Several hundred pounds ofsodium chloride regenerant per cubic foot of resin at saltconcentrations of from 6% to saturation are typically used.Alternatively, the resins can be used once for perchlorate adsorptionand then thrown away instead of being regenerated. In both cases, adifficult-to-deal-with perchlorate-loaded end product is formed. Theloaded resin can not be safely discarded in ordinary land fills and thelike because of fears of its perchlorate content reentering theenvironment. Attempts to bacterially break down the perchlorate contentof the concentrated sodium chloride brine have been unsuccessful becausethe bacteria are generally inactivated by the high salt levels. Forexample, Tina M. Gingras and Jacimaria R. Batista reported in J.Environ. Monit. (2002), 4, 96-101, that as little as 0.5% sodiumchloride present in a bioremediation environment lowered perchloratedegradation activity by 30% while 1.0% sodium chloride reduced activityby 60%.

What is needed, and what this invention provides, is a process forremoving perchlorate from perchlorate-loaded ion exchange resins withoutgenerating large quantities of intractable regeneration products. Thisinvention also provides a new form of ion exchange resin which iscapable of removing perchlorate ions from solution and directly breakingthe perchlorate down to nonperchlorate species in situ.

STATEMENT OF THE INVENTION

It has now been found that the perchlorate load present on aperchlorate-loaded ion exchange resin can be reduced, and in some casesvirtually completely eliminated, by contacting the loaded resin in situwith a perchlorate-destroying microorganism fluid product. Thisperchlorate-destroying microorganism fluid product can be a suspensionof cultured perchlorate-destroying microorganism. It also can be asupernatant obtained from such a suspension.

Thus, in one overall aspect, this invention provides a method forreducing the level of perchlorate load on perchlorate-loaded ionexchange resin. This general method includes the steps of obtainingperchlorate-loaded ion exchange resin, and directly contacting theperchlorate-loaded ion exchange resin with a perchlorate-destroyingmicroorganism fluid product under conditions leading to conversion ofthe perchlorate load on the resin to nonperchlorate reaction products.These conditions are most commonly referred to as facultative oranaerobic conditions. The nonperchlorate reaction products include oneor more of chlorate, chlorite, hypochlorite and chloride. This givesrise to a treated ion exchange resin having reduced perchlorate loadrelative to the perchlorate-loaded ion exchange resin.

This advantageous process can be used in a variety of settings includingnot only settings in which the treated ion exchange resin is recoveredand recycled for reuse but also settings in which the treated ionexchange resin is more safely disposed of by reason of its reducedperchlorate load.

Therefore, in another aspect, this invention can be embodied as a methodfor regenerating perchlorate-loaded ion exchange resin. This methodinvolves first obtaining perchlorate-loaded ion exchange resin from awater treatment zone. This is a zone in which the resin is used toremove perchlorate from a perchlorate-contaminated water stream and thusto reduce the perchlorate level in that water stream. Thisperchlorate-loaded resin is then directly contacted with aperchlorate-destroying microorganism fluid product under conditionsleading to conversion of perchlorate load on the resin to nonperchloratereaction products and generation of a treated ion exchange resin havingreduced perchlorate load relative to the perchlorate-loaded ion exchangeresin. These conditions and reaction products were described earlier.The treated resin is recovered and typically, after rinsing and othersuitable steps, is recycled to a water treatment zone for further useremoving perchlorate from a perchlorate-contaminated water stream.

In another aspect this invention can be embodied as a method for safelydisposing of perchlorate-loaded ion exchange resin This embodimentinvolves obtaining perchlorate-loaded ion exchange resin, and, prior todisposal, directly contacting the perchlorate-loaded ion exchange resinwith a perchlorate-destroying microorganism fluid product underconditions leading to conversion of perchlorate load on the resin tononperchlorate reaction products and generation of treated ion exchangeresin having reduced perchlorate load relative to the perchlorate-loadedion exchange resin. After the perchlorate level in the resin as beenreduced to a safe level, the treated ion exchange resin is disposed of.

This invention can also be embodied as part of overall processes fortreating perchlorate-contaminated water. In one such process,perchlorate-contaminated feed water is obtained and then contacted withan anion exchange resin having an affinity for perchlorate therebyforming a reduced perchlorate content product water andperchlorate-loaded ion exchange resin. The perchlorate-loaded ionexchange resin and the reduced perchlorate content product water areseparated and the product water is put to use as a water source fordomestic, industrial or agricultural applications including use asdrinking water. The perchlorate-loaded ion exchange resin is thencontacted with a perchlorate-destroying microorganism fluid productunder conditions leading to conversion of perchlorate load on the resinto nonperchlorate reaction products and generation of treated ionexchange resin having reduced perchlorate load relative to theperchlorate-loaded ion exchange resin. The treated ion exchange resincan then be safely disposed of or can be rinsed and returned to usetreating perchlorate-contaminated feed water.

This invention can also provide a process to reduce perchlorate levelsin brines. In this process the feed water is contacted with a firstanion exchange resin having an affinity for perchlorate, nitrate andsulfate thereby removing perchlorate, nitrate and sulfate from the feedwater and forming a reduced perchlorate, nitrate and sulfate contentproduct water and a perchlorate, nitrate and sulfate-loaded first ionexchange resin. The product water is separated from the perchlorate,nitrate and sulfate-loaded first ion exchange resin. The perchlorate,nitrate and sulfate-loaded first ion exchange resin is contacted withbrine, under conditions leading to the displacement of the perchlorate,nitrate and sulfate ions off of the resin into the brine. This yields aperchlorate, nitrate and sulfate-loaded spent brine and introduction ofchloride ions onto the first ion exchange resin to yield a regeneratedfirst resin. The perchlorate, nitrate and sulfate-contaminated spentbrine and the regenerated first resin are separated and the resin can berinsed and reused, if desired.

In this process the separated spent brine is then contacted with asecond anion exchange resin having an affinity and selectivity forperchlorate. This leads to removal of the perchlorate from the spentbring and formation of a reduced perchlorate content treated spent brineand a perchlorate-loaded second ion exchange resin. This reducedperchlorate-content spent brine typically has a low enough perchloratecontent to be suitably discharged into a disposal well or brine line.The perchlorate-loaded second ion exchange resin is then directlycontacted with a perchlorate-destroying microorganism fluid productunder conditions leading to conversion of perchlorate load on the resinto nonperchlorate reaction products and generation of treated ionexchange resin having reduced perchlorate load relative to theperchlorate-loaded ion exchange resin. This second resin can be reusedin the manner just described.

In additional aspects, this invention provides equipment and systems forcarrying out these methods and processes. For example the invention canbe embodied as a system for treating a perchlorate-loaded ion exchangeresin to reduce its perchlorate load to the point that it can berecycled and reused or to a point that it can be safely disposed of.Such a system includes a first reaction zone containing a culturecomprising a perchlorate-destroying microorganism strain, an aqueousmedium, and nutrient for the microorganism strain. This first reactionzone is maintained at conditions promoting the growth of theperchlorate-destroying microorganism strain. The system also includes asecond reaction zone containing perchlorate-loaded anion exchange resin,means for recovering a perchlorate-destroying microorganism fluidproduct from the culture in the first reaction zone and means forfeeding the recovered perchlorate-destroying microorganism fluid productto the second reaction zone into contact with the perchlorate-loadedanion exchange resin. This second reaction zone is operated atconditions under which the perchlorate-destroying microorganism fluidproduct reacts with the perchlorate load present on theperchlorate-loaded anion exchange resin and converts perchlorate to nonperchlorate reaction products thereby producing a reducedperchlorate-load anion exchange resin. This system will also includeeither means for discarding the reduced perchlorate-load resin or meansfor rinsing and recovering the reduced perchlorate load resin forrecycle and reuse.

Alternatively, the invention can be embodied as a system for reducingthe perchlorate content of perchlorate-contaminated water. This systemincludes a first reaction zone containing a culture comprising aperchlorate-destroying microorganism (bacteria) strain, an aqueoussubstrate and nutrient for the bacterial strain. The first reaction zoneis maintained at conditions promoting the growth of theperchlorate-destroying microorganism strain and includes a separator orother means for recovering a perchlorate-destroying microorganism fluidproduct from the culture in the first reaction zone. This system alsoincludes a second reaction zone. This second zone or vessel contains ananion exchange resin having an affinity for perchlorate present in theperchlorate-contaminated water supply and is equipped with means forfeeding the perchlorate-contaminated water to the second reaction zoneinto contact with the anion exchange resin under conditions permittingthe resin to remove perchlorate from the perchlorate-contaminated water.This yields the desired reduced perchlorate content product water andperchlorate-loaded ion exchange resin. A suitable solid/liquid separatoris provided to separate the reduced perchlorate content product waterfrom the perchlorate-loaded ion exchange resin. Once the ion exchangeresin is loaded with perchlorate it is removed from service. Theperchlorate-destroying microorganism fluid product recovered from thefirst reaction zone is conducted into contact with the loaded resin inthe second zone at conditions under which the perchlorate-destroyingmicroorganism fluid product reacts with the perchlorate-load present onthe perchlorate-loaded anion exchange resin converting perchlorate tononperchlorate reaction products thereby producing a reducedperchlorate-load anion exchange resin. This system additionally includesmeans for rinsing and otherwise recovering the reduced perchlorate loadanion exchange resin for reuse or disposal.

Yet additionally, the invention can also be embodied as a system forpurifying water and generating a safely disposable reducedperchlorate-level salt brine side product. In this system there is afirst reaction zone containing a culture comprising aperchlorate-destroying microorganism strain, an aqueous substrate,nutrient for the bacterial strain, said first reaction zone maintainedat conditions promoting the growth of the perchlorate-destroyingmicroorganism strain. The system includes means for recovering aperchlorate-destroying microorganism fluid product from the culture inthe first reaction zone. There is a second reaction zone containing afirst anion exchange resin having an affinity for perchlorate, nitrateand sulfate present in the perchlorate-contaminated water supply. Meansare provided to feeding the contaminated water to the second reactionzone into contact with the first anion exchange resin under conditionspermitting the resin to remove perchlorate, nitrate and sulfate from thecontaminated water thereby forming a reduced perchlorate, nitrate andsulfate content product water and perchlorate nitrate and sulfate-loadedion exchange resin. A separator separates the reduced perchlorate,nitrate and sulfate content product water from the perchlorate, nitrateand sulfate-loaded first ion exchange resin. The loaded first anionexchange resin formed in the second reaction zone with a salt brineunder perchlorate, nitrate and sulfate displacing conditions therebyforming a perchlorate, nitrate and sulfate-loaded spent brine and areduced perchlorate, nitrate and sulfate-content regenerated first resinand means for separating the perchlorate, nitrate and sulfate-loadedbrine from the regenerated first resin. The system also includes a thirdreaction zone containing a second anion exchange resin having enhancedaffinity for perchlorate over nitrate and sulfate and means for feedingthe perchlorate, nitrate and sulfate-loaded spent brine to said thirdreaction zone into contact with the second anion exchange resin underconditions permitting the resin to preferentially remove perchloratefrom the contaminated spent brine thereby forming a reduced perchloratecontent spent brine which can be safely passed to disposal andperchlorate-loaded second ion exchange resin. The perchlorate-loadedsecond resin is isolated and contacted with the perchlorate-destroyingmicroorganism fluid product recovered from the first reaction zone. Thiscontacting is at conditions under which the perchlorate-destroyingmicroorganism fluid product reacts with the perchlorate-load present onthe perchlorate-loaded anion exchange resin converting perchlorate tononperchlorate species and thereby producing a reduced perchlorate-loadanion exchange resin. This resin may be discarded or preferablyrecovered and reused.

In an additional aspect this invention provides a new form of ionexchange resin particularly designed to remove perchlorate contaminant.This resin product comprises a solid, particulate, porous polymerstructure carrying chemical moieties capable of associating with ananion such as chloride and capable of exchanging that anion forperchlorate. The particulate porous structure additionally has a film ofperchlorate-destroying microorganisms adsorbed onto its surface.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention will be further described with reference being made tothe accompanying drawings in which all of the Figures are semicross-sectional schematic elevational views of representative systemsembodying this invention and in which:

FIG. 1 shows a basic system of this invention in which the microorganismculture liquid product is a suspension of microorganisms;

FIG. 2 shows a system in which the microorganism culture liquid productis a liquid phase separated from the suspension of microorganisms;

FIG. 3 shows the system of FIG. 2 with several additional featuresincorporated into its flow scheme; and

FIG. 4 shows the system of FIG. 2 adapted to treat a perchlorate-ladenbrine stream feed.

DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention relates to the use of microorganisms to break downperchlorate load on anion exchange resins. The invention is depicted ina number of different process settings with a variety of feedstocks.Accordingly, this description of preferred embodiments will be brokendown into the following sections:

The Ion Exchange Resins

The Perchlorate-destroying Microorganisms

The Microorganism-coated Resin Product

Representative Feedstocks

Overall Process Descriptions and Process Flows

Process Conditions

Water Treatment with Microorganisms-Coated Resin

These sections will then be followed by Examples

The Ion Exchange Resins

The ion exchange resins which are loaded with perchlorate and treated inaccord with the invention are generally classed as strong base resins.

These resins are based on various polymer structures such as polystyrenewith cross-linkers and with appropriate active groups such as quaternaryammoniums attached. Representative resins include:

-   Prolate Strong Base Resins Type 1 and Type 2-   Amberlite IRA-400-   Amberlite IRA-900-   Dowex SBR-   Ionac ASB-1-   Ionac AFP-100-   Dowex SBR-P-   Dowex 11-   Duolite A-102-D-   Ionac ASB-2-   Amberlite IRA-93-   Amberlite IR-45-   Purolite A-400-   Purolite A-520-E-   Purolite A-600-   Ionac A-260-   Dowex WGR-   Sybron SR6-   Sybron SR7-   Reillex™HPQ Resins (based on polyvinyl pyridine polymers)-   Nitrex-   Resintech SIR 100-   Rohm and Haas Acrylic Resin

Other ion exchange resins which are applicable to the invention arestrong acid or weak base type resins such as:

-   Amberlite IR-120-   Ionac C-20-   Prolate C-100-   Ionac C-270-   Amberlite-200-   Ionac CFS

Generally, the strong base type I resins, particularly those based onpolystyrene backbones, give good overall results removing perchlorateand are preferred.

Among these resins, excellent results have been attained using theSybron SR6 resin. This is a resin having quaternary aminefunctionalities and three butyl groups in these quaternary amine groups.Sybron SR7 resin gives similarly excellent results. This is a similarquaternary amine-based resin but with three propyl groups in itsquaternary amine groups. The SR7 resin has been observed to have aparticularly high selectivity for perchlorate ions.

The Perchlorate-Destroying Microorganisms

This invention employs a perchlorate-reducing microorganism or, moretypically, a mixture of two or more such organisms. Representativemicroorganism-containing compositions include the mixed bacterialcultures present in classic municipal sludge (see U.S. Pat. No.3,755,156 (1973)); in activated sludge (see GR-1 in Rikken, G. B, et al.Appl. Microbial. Biotechnol. (1996) 45:420); and the BAU culture takenfrom Clark County, Nevada waste water treatment plants (see Gingras, T.M, et al. J. Environ. Monit. (2002) 4:96-101; Wohanella succinogenesHAP-1 of U.S. Pat. No. 5,302,285; Stan CKB from paper mill waste (seeBruce, R. A, et al. Environ. Microbial. (1999) 1:319); stain PPA D8 KJKJ3 and KJ4 reported by B. E. Lodan Appl. Environ. Microbial. (2001)67:2499, Ideonella dechloratoms and Acinebacter thermotoleranticus.These are merely representative of the general class of bacteria thatcan be used in the present process.

Additional microorganism sources include pathogen-free sludge, brewerysludge, mixed cultures and the like. In general any microorganism thatcan break down perchlorate can be suitable for use in this process.

These microorganisms are suitably cultured (grown out) in an aqueousmedium in the presence of suitable nutrients such as sugars, loweralcohols, (e.g. methanol, ethanol, isopropanol, carbon sources and thelike. The culture can be in the form of a suspension of microorganismsin the aqueous medium. The actual material that contacts the loadedresin particles is most commonly a fluid product which is defined hereinto be either a suspension of the organisms in the aqueous medium or arelatively microorganism-free liquid phase separated from the suspensionsuch as be decantation, centrifugation, filtration, screening, or thelike. This latter fluid product is referred to herein as a microorganismculture “supernatant”.

The Microorganism-Coated Resin Product

This invention provides a new resin product useful in the removal ofperchlorate from aqueous feedstocks. It is a combination of ion exchangeresin and biological materials. The material is prepared in thefollowing steps:

-   1. A particulate anion exchange resin capable of exchanging chloride    or the like for perchlorate is selected. Representative suitable    resins are described hereinabove.-   2. Perchlorate is adsorbed (exchanged) onto the resin from an    aqueous solution.-   3. The resin with adsorbed perchlorate is added to a bioreactor    containing perchlorate-degrading microorganisms. Representative    suitable microorganisms are described above.-   4. The microorganisms are allowed to grow on the surface of the    resin until at least a substantial fraction and preferably    essentially all of the adsorbed perchlorate is consumed.-   5. The resin having a thin film of microorganisms on the surface of    the particles is removed from the reactor and dried at room    temperature or fixed according to methods known in the art.

The product consists of ion exchange resin particles with a thin film ofperchlorate-destroying microorganisms fixed to the surface of the ionexchange particles.

This new form of resin can be used to remove perchlorate fromperchlorate-containing aqueous feedstreams in a single step in which theperchlorate present in the feedstream is adsorbed onto the exchangesites on the resin particles. Once there the perchlorate is converted tononperchlorate species by the microorganisms affixed to the surface ofthe resin particles.

Representative Feedstocks

The resins that are treated with the perchlorate-destroyingmicroorganism are resins which have become partially or relativelycompletely loaded with perchlorate ion relative to theirperchlorate-adsorbing capacity. In most settings, it is desirable toremove perchlorate quite completely. Often as a resin becomes partiallyexhausted on an absolute scale its performance drops off slightly. Thiscan be signal to consider to consider it “exhausted” and to remove itfrom service. This can occur when as few as 30 or 40% of the totalavailable capacity has been used up. This phenomenon will be seen in thepresent examples where resins were deemed suitable for regeneration whenabout 40-45% of their total capacity was exhausted. These resins canbecome loaded in service in an ion exchange-based water purificationunit. The term “water purification” is used in a broad sense to includethe purification of not only ground water, surface run off, water foundin bodies of water, streams, rivers and the like drinking water sourcebut also to include commercial, industrial and agricultural watersources such as plant effluents, agrarian run offs, sewage and the like.

In all of these settings, the water being purified must contain anunacceptably high level of perchlorate ion. That is a level ofperchlorate ion greater than a few parts per billion. This feed watercan contain up to as many as many part per million of perchlorate and insome industrial settings can contain tens or even up to 100 parts permillion of perchlorate. It will be appreciated that the invention wouldwork with resins loaded by treating water with even higher perchloratecontents. In all of these settings, it is very likely, if not the rule,that there will be other anions which will be picked up by the ionexchange resin. Many of these ions such as sulfate and nitrate, whilenot as troublesome as perchlorate, are not particularly desirable indrinking water so their exchange onto the resin is generally welcomed.These ions are typically present at levels considerably higher, often byfactors of a thousand or more, than perchlorate. A representative feedwater of this type could contain from about 10 to 250 ppb ofperchlorate, and 1 to 100 ppm of nitrate and/or sulfate.

Other ions such as heavy metal-based anions for example arsenate arealso regularly removed from the feed water when it is contacted with theresin. Thus a loaded resin bed may be substantially loaded withperchlorate ions in some cases and in others may have secondary ions asits predominant load.

In one special setting, the feedstock streams subjected to purificationby contact with the resin are themselves formed in an ion exchangeprocess and are, for example, the rinse water and the contaminatedaqueous brines generated during regeneration of ion exchange resins.

While perchlorate is one of the most readily adsorbed ions and candisplace other species such as nitrate and sulfate, in practice the ionexchange resin is commonly sent to regeneration or disposal once it isloaded with perchlorate and other ions exchanged out of the feed stream.

Overall Process Descriptions and Process Flows

FIG. 1 shows a representative apparatus for contacting the resin withthe microorganisms. Perchlorate-loaded resin 8 is charged to vessel 10or is formed in vessel 10 by initially charging fresh resin to thevessel and loading it with perchlorate by passing perchlorate-ladenuntreated water over it via line 4. The resin will adsorb theperchlorate in exchange for a nonperchlorate ion (usually chloride) andyield perchlorate-free treated water which can be removed via line 6.This loading is exactly what happens when the resin is in servicepurifying water. A suspension of microorganisms; methanol, ethanol orother nutrients; suitable microorganism-growth salts and an aqueoussubstrate are charged to vessel 12 via line 14 and agitated to assistgas release and to prevent stratification. Once the bacteria hascultured and grown, the biomixture is fed through line 16 to vessel 10where it reacts with the perchlorate present in resin 8. The tworeactors are maintained under anaerobic conditions by use of nitrogencaps or the like. As the bacteria consumes the nutrients andperchlorate, biomass is generated that is carried off from vessel 10 vialine 18 back to vessel 12 or to waste via line 22. This biomass invessel 12 forms a sludge which is removed via line 20.

Following the reaction of perchlorate with the microorganisms, the resincan be washed, cocurrent or countercurrent, with water supplied, forexample, via line 24. The biomass and microorganisms can be removed withthe used wash water via line 26-26′ or recycled via line 28. Thiswashing generally removes microorganisms from the resin. Additionalclean-up steps such as steaming, acid rinsing, hot water treatment andthe like can be applied to the treated resin, either in place (in vessel10) or in other process equipment not shown.

FIG. 2 shows a variation on the general process depicted in FIG. 1. Thesame numbers will be applied to the same equipment, when applicable.FIG. 2 depicts system 200 in which the perchlorate-destroyingmicroorganisms are cultured in a two stage reactor/separator. Asuspension of one or more microorganisms, methanol or other loweralcohol or sugar microorganism nutrient, suitable microorganism-growthsalts and an aqueous substrate are again added via line 14 to vessel 12,equipped with agitator 30. Once the microorganism(s) are cultured andpermitted to grow out, a suspension of microorganisms is passed via line32 to separator/settler 34 which is equipped with agitator 36 to assistin the settling of the solids and achievement of a substantiallysolids-free supernatant microorganism culture liquid product. Thissolids-free liquid is drawn off and transferred via line 16 to vessel 10which contains a bed 8 of perchlorate-loaded ion exchange resin.

System 200 provides line 18, through which the solids-free liquid can bereturned to settler/separator 34 after passing over the resin bed.Overflow line 26/28 provides a route by which wash water can be takenoff of the resin bed and passed to vessel 34. Sludge and other biomasscan be removed from settler 34 via line 20 and optionally recycled tobioreactor 12 via line 40. Usually, at least a portion of the biomassand sludge is removed via line 20. Supernatant, separated in settler 34,can also be recycled to bioreactor 12 via line 42 for refreshment.

Now turning to FIG. 3, system 300 is shown. System 300 is identical tosystem 200, just described, except that it includes three optionaladditions incorporated into line 16 to modify or treat the culturedmicroorganism liquid product being passed via line 16 into contact withthe perchlorate-loaded resin present in bed 8. These optional additionsinclude a filter 44.

Filter 44 is a filter designed to retain solids present in the liquid.This is nominally a 15 micron to 100 micron particle retention filterand more typically a 20 to 50 micron particle retention filter. We haveused a nominal 25 micron particle retention filter in our work and findit to provide good results. Filter 44 can be used to reduce themicroorganism particles as well as any particulate sludge or biomass.This may be important if the product water is to be potable water.

System 300 also optionally contains ion exchanger 46. This is an in-lineion exchanger filled with a perchlorate-selective ion exchange resin. Itis generally desired to reduce the level of perchlorate on the resin inbed 8 to as low a level as possible. It is to be understood that theperchlorate ions adsorbed onto resin 8 are to a modest extent in anequilibrium with nonsorbed ions such that as liquid is flowing over theresin in bed 8, some small, but detectable, amounts of perchloratedissociate from the resin and enter the liquid flowing past. This ionexchanger 46, with its perchlorate-selective resin, eliminates thechance that this desorbed perchlorate is readsorbed onto the resin inbed 8.

System 300 can also include a bed of activated carbon in in-line filter48 This carbon bed can remove odors and prevent their build up it alsomay provide a nutritious environment for any microorganisms circulatingin the liquid.

FIG. 4 shows system 400. System 400 resembles system 200 with oneaddition. It includes ion exchange vessel 50 loaded with resin bed 52.Resin bed 52 is a typical spent resin bed from use in perchlorateremoval duty. Its resin contains a mixture of nitrate and sulfate ionsadsorbed on its resin in addition to perchlorate. These ions would havebeen present in feed water fed over the resin via line 54. Productwater, containing reduced levels of perchlorate, nitrate and sulfateions is removed via line 56. To regenerate the spent resin, a brinesolution, typically containing on the order of 4-8% by weight sodiumchloride, is fed via line 58 and passed over resin bed 8 where itdisplaces the perchlorate, nitrate and sulfate ions present on the spentresin. The effluent brine from vessel 50, which contains perchlorate,nitrate and sulfate ions, is transferred via line 60 to vessel 10 whichcontains a perchlorate-selective resin as bed 8. This resin bed adsorbsthe perchlorate onto the resin in bed 8 and yields a relativelyperchlorate-free but nitrate and sulfate-rich effluent out of vessel 10.This effluent is removed via line 22, most typically fordiscard/disposal into a commercial brine disposal line or well. This isadvantageous in that the untreated brine stream with its substantialperchlorate concentration can not be fed into typical commercial brinedisposal lines and wells.

Once the resin bed 8 is loaded with perchlorate, the flow of brine isstopped, rinse water is passed over the resin via line 62 to removal vialine 22. This removal of brine is often needed to prevent the high saltlevel from deactivating the microorganisms which are next fed over theresin bed 8. Once the bed 8 has been rinsed, microorganism cultureliquid product is fed via line 16 from separator 34 and the processdescribed with reference to FIG. 2 is carried out to permit theperchlorate load on the resin in bed 8 to be reacted to nonperchlorateproducts.

In the process depicted with reference to system 400, it will be notedthat perchlorate was separated from nitrate and sulfate by desorbing andeluting all of the three ions simultaneously off of resin bed 52 withbrine. Thereafter resin selectivity was relied upon to preferentiallyadsorb the perchlorate content from the brine. In a variation on this,the three ions can be adsorbed onto the resin bed 8 in vessel 10 from aperchlorate, nitrate and sulfate-contaminated water source substantiallyas depicted in FIG. 2. The perchlorate can be digested, using themicroorganism culture liquid product and thereafter, once theperchlorate level has been suitably reduced to a level that any residualperchlorate will not be a disposal issue, the bed of resin 8 in reactor10 which will then still contain substantial levels of nitrate andsulfate can be treated with brine to desorb the nitrate and sulfate andminor amounts of perchlorate, remaining on the resin. The loaded brine,so formed, will have minimal perchlorate content and can be discarded byroutine channels.

Process Conditions

Contacting the resin with the microorganisms is carried out in batch orcontinuous mode. The amount of microorganism suspension should be enoughto completely immerse the resin particles. The concentration ofmicroorganisms in the suspension will be in part determined by theorganism itself and is typically defined by the equilibriumconcentration which the organism achieves as it is grown.

Contacting is carried out for a prolonged period of time, such as atleast about 1 or 2 days and up to 2-3 or even 4-5 weeks. The extent ofconversion can be monitored and conversion of essentially all theperchlorate contamination can be achieved. The contacting can beconducted at any temperature at which the microorganisms retainviability, such as from about 5° C. to about 50° C. and especially from15° C. to about 40° C.

The influent water should not contain large amounts of dissolved oxygento maintain an anaerobic condition in which the microorganisms canflourish and degrade perchlorate. From time to time, backwashing willremove any excess microorganism build up from the column.

While the process can, in theory be carried out in a static mode, betterresults are generally achieved when the microorganism fluid product isflowed over the perchlorate-loaded resin. Representative flow rates arefrom about 0.1 volumes of flow per volume of resin per hour to about 10volumes per volume per hour.

Ion Exchange Water Treatment with Microorganism-Coated Resin

A microorganism-coated ion exchange resin as described above can be usedin water treatment to remove perchlorate from a drinking water supply.The coated resin material is placed in a column as in the usual columnconfiguration used in an ion exchange process. The untreated water isfed into the top of the column (with a small amount of organic nutrientmaterial such as ethanol) where it is contacted with themicroorganism-coated ion exchange material. The perchlorate is adsorbedonto and concentrated by the resin. The perchlorate-degrading bacteriabreaks down the perchlorate on the resin as the microorganism expandsand as the perchlorate is adsorbed.

The present invention will be further described by the followingexamples. These are provided solely to illustrate the practice of thisinvention and are not to be construed as limitations on its scope:

EXAMPLE 1 Bench Scale Tests

The following is a description of bench scale tests that showperchlorate can be degraded while it is adsorbed on an ion exchangeresin.

Anaerobic digestion was demonstrated to be very efficient in degradingperchlorate that has been adsorbed onto A520E resin. The resin wassaturated with a perchlorate solution. A sample of conventional sewagesludge was obtained and grown up under anaerobic conditions with addedlower alcohol nutrient in an aqueous medium. A sample of this suspensionof microorganisms was placed in a bioreactor. The saturated resin samplewas placed in a pair of perforated holders to allow the suspension ofmicroorganisms to contact the resin. The reactor was purged withnitrogen and maintained under anaerobic conditions. The suspension andthe loaded resin were allowed to remain in contact for two weeks.

One of the two samples of the resin was removed from the reactor after aperiod of two weeks and bacterial sludge was removed by rinsing withwater. About 10 ml of rinsed, bio-treated resin was placed in a flaskwith 400 ml of perchlorate solution (initial concentration was 1,291mg/l). After 24 hrs of mixing in a shaker, the concentration ofperchlorate decreased to 410 mg/l. This result indicated that about 40%of ion-exchange capacity was recovered by two weeks of incubation in theanaerobic digester.

These values were calculated as follows:

-   1. The amount of ClO₄ removed by bio-treated resin    =(1291 mg/l−410 mg/l)×0.41    =352.4 mg-   2. Ion-exchange (perchlorate) capacity of bio-treated resin    =352.4 mg/10 ml    =35.24 mg/ml of resin    =0.354 meq/ml of resin-   3. Minimum ion-exchange (perchlorate) capacity of virgin A520E resin    =0.9 meq/ml-   4. The efficiency of bio-treatment (bio-regeneration) during 2 weeks    of incubation in the anaerobic digester    =0.354/0.9    =39.3%

The second resin sample was allowed to remain in the digester for anadditional two weeks. Its capacity for perchlorate adsorption was thenmeasured. It was found that a greater percentage of the resin capacitywas restored by four weeks of treatment in the digester but that only upto about 50% regeneration was attained. Although not understood withcertainty, one explanation for this limited regeneration is that atstatic conditions some kind of boundary layer is built up around theresin. (This is possibly a protective microfilm of some sort or ionicconcentration gradient. The resin does not pick up organics). Thisboundary layer grew thick enough to slow down the bioreduction reaction.

EXAMPLE 2 Effect of Agitation and Flow Systems

As shown in Example 1, at zero flow rate or very low rates only about40% of the perchlorate can be removed regardless of time (days) in thereactor. However, with agitation or with a high flow rate, such as flowsystem space velocities of from about 0.1 to about 10 v/(v×hrs)Vv 100%regeneration can be achieved using a suspension of microorganisms intimes as short as about 3 days.

EXAMPLE 3 Comparison of Use of Slurry and Supernatant FluidMicroorganism Products

In order to investigate the effect of pre-sedimentation on thebio-regeneration efficiency, two ion exchange columns loaded withperchlorate-loaded A-520-E resin were connected to the bio-regenerationsystems, with and without pre-sedimentation. The presedimentation zonewas as set forth in FIG. 2. A sewage sludge source of microorganisms asused in Example 1 was used. One column (A) was fed supernatant producedin a sedimentation basin (working volume 2.6 L) which was placed betweenthe bioreactor and Column A. Pickets, which rotated at 0.6-0.7 rpm, wereinstalled to prevent the bridging of sludge particles and to acceleratethe release of biogas. The second column, Column B was fed anaerobicsludge. Due to the high concentration of suspended solids (SS), it wasnot easy to pump anaerobic sludge to Column B continuously. So, Column Bflow to was operated intermittently (10 to 20 min per day) Column Bcould be described as a “zero” flow rate column. The averaged flow rateof Column A was 11.4 ml/min.

Water samples were taken every day from 3 sampling ports, the influentand effluent of Column A and the influent of Column B. Resin sampleswere taken out every day from each of the columns and isothermadsorption tests were conducted for the measurement of ion-exchangecapacity of the bio-treated resins. This test was conducted for 5 daysof operation.

The efficiency of bio-regeneration as a function of elapsed time wasmeasured. For the calculation of bio-regeneration efficiency, theaveraged perchlorate-exchange capacity of virgin A520E resin (1.12meq/ml) was used Since the resin, which was packed into the columns, wasonly partially exhausted (44.6%) by the perchlorate adsorption, thebio-regeneration efficiency should be compared to this portion. Column A(presedimentation) showed bioregeneration levels of from 38.9-47.7% withmost measurements reflecting 44% or better (based on the capacity ofvirgin resin or about 85-100% based on the fraction of sites adsorbingperchlorate. Column B (no presedimentation) showed bioregeneration tolevels of from 33.7% to 43.5% (based on the capacity of virgin resin orabout 75-95% based on the fraction of sites adsorbing perchlorate. It isclear that Column A had consistently higher bio-regeneration efficiencythan Column B. This result means that the supernatant can beadvantageously used as a bio-regenerating agent.

EXAMPLE 4 Application to Brine Treatment

The removal of perchlorate from a resin as described above can beapplied to a resin loaded with perchlorate from a brine that is itselfgenerated in a resin regeneration process as follows.

Ground water containing about 20 ppb of perchlorate and part per millionlevels of nitrate and sulfate can be treated with an acrylic resin.Approximately 500 bed-volumes of water can be treated. The resin isregenerated by contact with a strong salt brine (6-8% w NaCl). Thisdesorbs the perchlorate, nitrate and sulfate off of the resin. Theconcentration of perchlorate in the brine will be about 10 mg/L. Such abrine with this much perchlorate cannot be disposed of because ofregulatory requirements. The brine, however, can be treated with aperchlorate specific resin, such as A520E resin which preferentiallyadsorbs the perchlorate but also will typically pick up some nitrateand/or sulfate. When the perchlorate is transferred to the A520E resin,the concentration of perchlorate in the waste brine will be belowdetection levels and the treated brine is acceptable for disposal. Theconcentration of perchlorate on the A520E resin will be about 300 mg/L.

The perchlorate-loaded A520E resin can then be treated in a static orflow system with a suspension of perchlorate-destroying microorganismsor a supernatant from such a microorganism culture to remove theperchlorate as is described above. This resin can then be recycled totreat more brine with the sodium chloride in the brine displacing anyexcess nitrate or sulfate and preventing the resin from becomingsaturated with sulfate and nitrate which primarily remain in the brinefor disposal.

1. A system for reducing the perchlorate load on a perchlorate-loadedanion exchange resin and producing a reduced perchlorate load anionexchange resin comprising: a source of perchlorate-destroyingmicroorganism fluid product, a resin contact reaction zone containingperchlorate-loaded anion exchange resin and in which theperchlorate-loaded anion exchange resin is directly contacted with theperchlorate-destroying microorganism fluid product provided by thesource at conditions under which the perchlorate-destroyingmicroorganism fluid product reacts with the perchlorate load present onthe perchlorate-loaded anion exchange resin converting perchlorate tononperchlorate reaction products thereby producing a reduced perchlorateload anion exchange resin, and a separator for separating the reducedperchlorate load anion exchange resin from the perchlorate-destroyingmicroorganism fluid product.
 2. The system of claim 1 additionallyincluding a source of rinse water to rinse the reduced perchlorate loadanion exchange resin.
 3. The system of claim 1 wherein the source ofperchlorate-destroying microorganism fluid product comprises amicroorganism-containing reaction zone containing a culture comprising aperchlorate-destroying microorganism strain, an aqueous medium, nutrientfor the microorganism strain, said first reaction zone maintained atconditions promoting the growth of the perchlorate-destroyingmicroorganism strain.
 4. The system of claim 3 wherein the source ofperchlorate-destroying microorganism fluid product additionally includesa separator for recovering perchlorate-destroying microorganism fluidproduct from the culture in the microorganism-containing reaction zone.5. The system of claim 4 wherein the source of perchlorate-destroyingmicroorganism fluid product additionally includes a fluid deliverer forfeeding the recovered perchlorate-destroying microorganism fluid productto the resin contact reaction zone into direct contact with theperchlorate-loaded anion exchange resin.
 6. The system of claim 3additionally comprising a resin recoverer for recovering the rinsedreduced perchlorate load anion exchange resin from the resin contactreaction zone.
 7. The system of claim 6 wherein the conditions underwhich the perchlorate-destroying microorganism fluid product reacts withthe perchlorate load present on the perchlorate-loaded anion exchangeresin include flow contact of the fluid product with theperchlorate-loaded anion exchange resin.
 8. The system of claim 1wherein the nonperchlorate reaction products comprise at least one ofleast one of chloride, hypochlorite and chlorite.
 9. A system forreducing the perchlorate content of perchlorate-contaminated watercomprising: a source of perchlorate-contaminated water, a reaction zonecontaining an anion exchange resin having an affinity for perchloratepresent in the perchlorate-contaminated water, a fluid feeder forfeeding the perchlorate-contaminated water to the reaction zone intocontact with the anion exchange resin under conditions permitting theresin to remove perchlorate from the perchlorate-contaminated waterthereby forming a reduced perchlorate content product water andperchlorate-loaded anion exchange resin, a separator for separating thereduced perchlorate content product water from the perchlorate-loadedanion exchange resin, a source of perchlorate-destroying microorganismfluid product, a contactor for directly contacting theperchlorate-loaded anion exchange resin formed in the reaction zone withthe perchlorate-destroying microorganism fluid product at conditionsunder which the perchlorate-destroying microorganism fluid productreacts with the perchlorate-load present on the perchlorate-loaded anionexchange resin converting perchlorate to non perchlorate reactionproducts thereby producing a reduced perchlorate-load anion exchangeresin, and a separator for separating recovering the reduced perchlorateload anion exchange resin from the perchlorate-destroying fluid reactionproduct.
 10. The system of claim 9 additionally including a source ofrinse water to rinse the reduced perchlorate load anion exchange resin.11. The system of claim 9 wherein the source of perchlorate-destroyingmicroorganism fluid product comprises a microorganism-containingreaction zone containing a culture comprising a perchlorate-destroyingmicroorganism strain, an aqueous medium, nutrient for the microorganismstrain, said first reaction zone maintained at conditions promoting thegrowth of the perchlorate-destroying microorganism strain.
 12. Thesystem of claim 11 wherein the source of perchlorate-destroyingmicroorganism fluid product additionally includes a separator forrecovering perchlorate-destroying microorganism fluid product from theculture in the microorganism-containing reaction zone.
 13. The system ofclaim 12 wherein the source of perchlorate-destroying microorganismfluid product additionally includes a fluid deliverer for feeding therecovered perchlorate-destroying microorganism fluid product to theresin contact zone into direct contact with the perchlorate-loaded anionexchange resin.
 14. The system of claim 11 additionally comprising aresin recoverer for recovering the rinsed reduced perchlorate load anionexchange resin from the resin contact zone.
 15. The system of claim 14wherein the conditions under which the perchlorate-destroyingmicroorganism fluid product reacts with the perchlorate load present onthe perchlorate-loaded anion exchange resin include flow contact of thefluid product with the perchlorate-loaded anion exchange resin.
 16. Thesystem of claim 9 wherein the nonperchlorate reaction products compriseat least one of least one of chloride, hypochlorite and chlorite. 17.The system of claim 9 wherein the resin contact zone is the reactionzone.
 18. The system of claim 9 wherein the resin contact zone isseparate from the reaction zone.
 19. A system for reducing theperchlorate content of perchlorate-contaminated water that additionallycontains at least one of nitrate and sulfate comprising a source ofnitrate and/or sulfate-containing, perchlorate-contaminated water, afirst reaction zone containing a first anion exchange resin having anaffinity for perchlorate and nitrate and/or sulfate present in theperchlorate-contaminated water, a fluid feeder for feeding said nitrateand/or sulfate-containing perchlorate-contaminated water to the firstreaction zone into contact with the first anion exchange resin underconditions permitting the resin to remove perchlorate and nitrate and/orsulfate from the perchlorate-contaminated water thereby forming areduced perchlorate, nitrate and sulfate-content product water andperchlorate, nitrate and sulfate-loaded first anion exchange resin, aseparator for separating the reduced perchlorate, nitrate andsulfate-content product water from the perchlorate, nitrate andsulfate-loaded first anion exchange resin, a salt brine source providinga salt brine in contact with the separated perchlorate, nitrate andsulfate-loaded first anion exchange resin under nitrate, sulfate, andperchlorate displacing conditions thereby forming a nitrate, sulfate andperchlorate-loaded spent brine, and a reduced nitrate, sulfate andperchlorate-content regenerated first anion exchange resin, a separatorfor separating the nitrate, sulfate and perchlorate-loaded spent brinefrom the regenerated first anion exchange resin, a second reaction zonecontaining a second anion exchange resin having enhanced affinity forperchlorate over nitrate and sulfate, a fluid feeder for feeding thenitrate, sulfate and perchlorate-loaded spent brine to the secondreaction zone into contact with the second anion exchange resin underconditions permitting the resin to preferentially remove perchloratefrom the nitrate, sulfate and perchlorate-loaded spent brine therebyforming a reduced perchlorate content spent brine and perchlorate-loadedsecond anion exchange resin, a separator for separating the reducedperchlorate-loaded spent brine from the perchlorate-loaded second anionexchange resin, a source of perchlorate-destroying microorganism fluidproduct, a contactor for directly contacting the perchlorate-loadedsecond anion exchange resin formed in the second reaction zone with theperchlorate-destroying microorganism fluid product at conditions underwhich the perchlorate-destroying microorganism fluid product reacts withthe perchlorate-load present on the perchlorate-loaded second anionexchange resin converting perchlorate to nonperchlorate reactionproducts thereby producing a reduced perchlorate-load second anionexchange resin, and a separator for separating recovering the reducedperchlorate load second anion exchange resin from theperchlorate-destroying fluid reaction product.
 20. The system of claim19 additionally including a source of rinse water to rinse the reducedperchlorate load anion exchange resin.
 21. The system of claim 19wherein the source of perchlorate-destroying microorganism fluid productcomprises a microorganism-containing reaction zone containing a culturecomprising a perchlorate-destroying microorganism strain, an aqueousmedium, nutrient for the microorganism strain, said first reaction zonemaintained at conditions promoting the growth of theperchlorate-destroying microorganism strain.
 22. The system of claim 21wherein the source of perchlorate-destroying microorganism fluid productadditionally includes a separator for recovering perchlorate-destroyingmicroorganism fluid product from the culture in themicroorganism-containing reaction zone.
 23. The system of claim 22wherein the source of perchlorate-destroying microorganism fluid productadditionally includes a fluid deliverer for feeding the recoveredperchlorate-destroying microorganism fluid product to the resin contactreaction zone into direct contact with the perchlorate-loaded anionexchange resin.
 24. The system of claim 21 additionally comprising aresin recoverer for recovering the rinsed reduced perchlorate load anionexchange resin from the resin contact reaction zone.
 25. The system ofclaim 24 wherein the conditions under which the perchlorate-destroyingmicroorganism fluid product reacts with the perchlorate load present onthe perchlorate-loaded anion exchange resin include flow contact of thefluid product with the perchlorate-loaded anion exchange resin.
 26. Thesystem of claim 19 wherein the nonperchlorate reaction products compriseat least one of least one of chloride, hypochlorite and chlorite.